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arXiv · 2009.13544

Measurements of the z ~ 6 Intergalactic Medium Optical Depth and Transmission Spikes Using a New z > 6.3 Quasar Sample

Jinyi Yang·Feige Wang·Xiaohui Fan·Joseph F. Hennawi·Frederick B. Davies·Minghao Yue·Anna-Christina Eilers·Emanuele P. Farina·Xue-Bing Wu·Fuyan Bian·Fabio Pacucci·Khee-Gan Lee
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Abstract

We report new measurements of the intergalactic medium (IGM) Ly$α$ and Ly$β$ effective optical depth at $5.3 5.3$, $τ\propto(1+z)^{8.6\pm1.0}$. We then estimate the observed Ly$β$ effective optical depth using Ly$β$ forests and convert them to Ly$α$ optical depth for comparison, which provides additional constraints on the evolution of the IGM optical depth. The Ly$β$-based measurements are generally in agreement with the best-fit evolution obtained from Ly$α$ forests. Using this new sample, we identify 389 Ly$α$ and 50 Ly$β$ transmission spikes at $5.5<z<6.3$. The upper limits of Ly$α$ optical depth estimated using transmission spikes are well consistent with our best-fit evolution. The evolution in number density of these high-redshift transmission spikes suggests a rapid transition phase at the end of the reionization. Comparison of our optical depth measurements with hydrodynamical simulations indicates a IGM neutral hydrogen fraction $\langle f_{\rm HI}\rangle\gtrsim10^{-4}$ at $z=6$.

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Jinyi Yang, Feige Wang, Xiaohui Fan, Joseph F. Hennawi, Frederick B. Davies, Minghao Yue, Anna-Christina Eilers, Emanuele P. Farina, Xue-Bing Wu, Fuyan Bian, Fabio Pacucci, Khee-Gan Lee. 2020-09-28. Measurements of the z ~ 6 Intergalactic Medium Optical Depth and Transmission Spikes Using a New z > 6.3 Quasar Sample. https://doi.org/10.3847/1538-4357%2Fabbc1b

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